In a halogenoalkane (haloalkane or alkyl halide) a halogen (fluorine, chlorine, bromine or iodine) is bonded to an alkyl group by means of a single C-X bond. They are named as substituted alkanes …
And if there is more than one halogen in the molecule …
Halogenoalkanes are commonly used intermediates in organic synthesis. Halogens are more electronegative than carbon which means that these molecules have a polar C-X bond – this makes the molecules more reactive (and useful) than alkanes.
If you are completely new to organic chemistry, then I strongly suggest you start by getting your head around the terminology first!
Halogenoalkanes / haloalkanes react via a nucleophilic substitution mechanism (SN2)
Why are primary halogenoalkanes more reactive than secondary?
What difference does the halogen make? Why do tertiary halogenoalkanes react via the SN1 mechanism?
Elimination reactions in halogenoalkanes (E2 and E1 mechanism)
How to prepare a halogenoalkane
from an alkane, an alkene or by halogenation of an alcohol